We recommend forged pliers No. 1012 by C.S. Osborne & Co for professional applications. 
Their 2-stage jaws are suitable for small and larger zip fastener top stops. The pliers are sufficiently wide both at the front and at the second stage to safely take small and large stoppers and neatly press them.
Long handles allow you to press firmly and prevent the massive jaws from bending. High contact pressure is required especially for the reliable pressing of larger top stops RT20 and RT25 on zip fasteners with chain width of more than 7 mm.
Spring force closes. As a result, a top stop taken in the pliers is clamped between the jaws, even if you do not apply pressure. This makes it easy to optimally place a top stop in the pliers making it easier to position, slide on and align it in the correct position on the zip fastener tape.
Osborne pliers No. 1012 are almost indestructible and offer stability of value, because they work reliably even after years of use.
If it is needed to press a top stop on a zip fastener only occasionally, simpler crimping pliers can also be used. 
Compared to the professional Osborne pliers, its jaws made of simple structural steel are narrower and thinner. With frequent use, thin structural steel therefore wears faster on the jaws and at the joint. The jaw surfaces are often improperly aligned with each other, which is why it is more difficult to grip and hold the small top stop.
Using these pliers does not require many skills. At least you can press the smaller top stops quite neatly, as shown in the accompanying pictures.
